WO2018006694A1

WO2018006694A1 - Method for producing silicon tetrachloride

Info

Publication number: WO2018006694A1
Application number: PCT/CN2017/088427
Authority: WO
Inventors: 沈祖祥; 王姗
Original assignee: 成都蜀菱科技发展有限公司
Priority date: 2016-07-06
Filing date: 2017-06-15
Publication date: 2018-01-11
Also published as: CN106185950B; CN106185950A

Abstract

A method for producing silicon tetrachloride. The method comprises the following sequence of steps: a. grinding a SiO₂-containing material and a carbon-containing material separately to obtain a SiO₂ powder and a carbon powder; b. drying the SiO₂ powder and the carbon powder; c. uniformly mixing the dried SiO₂ powder and carbon powder to obtain a mixture; and d. continuously adding the mixture into a reactor vessel, then performing a chlorination reaction at a temperature of 800-1800°C to obtain a silicon tetrachloride product.

Description

Method for producing silicon tetrachloride

Technical field

The invention belongs to the field of silicon chemical industry, and in particular relates to a method for producing silicon tetrachloride.

Background technique

Silicon tetrachloride is used in the manufacture of organosilicon compounds such as silicates, silicone monomers, silicone oils, high temperature insulating varnishes, silicone resins, silicone rubber and heat resistant backing materials. High-purity silicon tetrachloride is a raw material for producing silane, trichlorosilane, dichlorodihydrosilane, polycrystalline silicon, high-purity silica, inorganic silicon compounds, and quartz fibers. Silicon tetrachloride is used in the military industry to manufacture smoke agents. It can be used in the metallurgical industry to manufacture corrosion-resistant ferrosilicon. It is an essential basic chemical raw material for large-scale industrial production, including gas phase white carbon and ethyl silicate. The production of optical fiber and other materials is the largest.

At present, the preparation methods of silicon tetrachloride mainly include the following:

(1) Preparation of silicon tetrachloride by reacting metal silicon or silicon alloy with chlorine or HCl

No. 4,044,109 discloses a process for the production of SiCl ₄ by the reaction of metallic silicon with HCl in the presence of an iron compound, wherein the iron compound comprises 10-43% of the total solids content. JP 3746109 B discloses a process for preparing SiCl ₄ by reacting metal silicon with HCl at a temperature of 250-500 ° C in the presence of Ni, Pd or a compound thereof. CN103420382B discloses a method for preparing SiCl ₄ by gas-solid synthesis reaction with chlorine gas in a bubbling bed using silicon powder as a main raw material without adding any catalyst, and the reaction temperature is 250-450 °C.

JPS59156908A discloses a method for preparing SiCl ₄ by reacting silicon iron as a raw material with chlorine gas at 350-1000 ° C, wherein when iron, ferric chloride or the like is accumulated in the reactor, the ferrosilicon feed is stopped, only to the reactor Chlorine gas is introduced into the medium; when the temperature of the reactor drops to ≤300 °C, the ferrosilicon raw material is added. No. 4,130,632 discloses a process for the formation of trichlorosilane or silicon tetrachloride by reacting silicon, an aluminum alloy with hydrogen chloride or a chlorine gas.

The above method uses metal silicon or a silicon alloy as a raw material, and the chlorine gas utilization rate is high. However, metal silicon or silicon alloys have higher smelting costs and high energy consumption. Therefore, the method has the disadvantages of high production cost, environmental friendliness, and high energy consumption. In addition, the reaction of metallic silicon with HCl produces hydrochlorosilanes such as SiHCI ₃ and SiH ₂ Cl ₂ , which makes the subsequent purification step of SiCl ₄ cumbersome. It is therefore difficult to apply these methods to achieve large-scale production of silicon tetrachloride.

(2) a mixture of SiO ₂ and carbon is reacted with chlorine to prepare silicon tetrachloride

In the early days, silicon carbide was used as a raw material to produce SiCl ₄ . For example, JPS 63117907 A discloses a method of obtaining SiCl ₄ by reacting silicon carbide having an average particle diameter of ≤10 μm with chlorine gas at a temperature of 600 to 900 °C. However, silicon carbide is relatively expensive and is therefore usually replaced by a mixture of SiO ₂ and C. According to the form of SiO ₂ , it can be further divided into: natural SiO ₂ , such as diatomaceous earth, quartz sand, quartz stone, silica, etc.; ash produced by industrial processes, such as large-scale electrochemical manufacturing process of silicon (such as metal silicon) , flue dust generated by the preparation process of silicon alloy, etc.; biomass burning ash rich in SiO ₂ and C. In this prior art, by the SiO _2, C C1 ₄ directly obtained reaction mixture and SiCl _4.

JP 1983 217 420 A discloses a method for preparing silicon tetrachloride by reacting a silicon-containing substance, carbon and chlorine at a high temperature, wherein the silicon-containing substance is in a slight contact with a gas discharged from a closed furnace for preparing metal silicon or ferrosilicon. Then cool down and catch the dust. JPH0218317A discloses a process for preparing a pellet by bonding water and glass with silica and carbon, and then reacting with chlorine gas at a high temperature to prepare silicon tetrachloride, wherein the silica is preferably silica and biomass burning ash.

The use of the gray powder as a raw material eliminates the grinding step compared to the use of natural SiO ₂ as a raw material, and directly obtains a powder having a small particle diameter and a large BET surface area. However, in order to prevent the particles from collapsing during the reaction, the problem that the fine powder easily flies out of the reactor usually requires the addition of a binder to form a pellet. The added binder inevitably brings impurities to the reaction, which lowers the purity of the product and causes difficulties for subsequent purification steps. And in these methods, the supply of the gray powder raw material is not stable.

Further, in the prior art for preparing silicon tetrachloride using natural SiO ₂ , a catalyst is often added to lower the reaction temperature and increase the reaction rate. For example, CA 1230465 A discloses a process for preparing silicon tetrachloride by reacting a material comprising SiO ₂ with chlorine gas in the presence of a catalyst of carbon and a catalytic concentration, the catalyst being a transition metal halide, the fifth main group of the periodic table. Or a sub-group of chlorides, or a mixture thereof. Other catalysts used in the preparation of silicon tetrachloride also include boride such as boric acid, boron trioxide, sodium tetraborate, potassium tetraborate, gaseous boron trichloride, and the like (see JP1982042524A, US4490344 and JP1982007813A); potassium compounds, for example Potassium carbonate, potassium chloride, potassium sulfate, potassium nitrate (see JPS62252311A); sulfur or sulfides such as carbon disulfide, sulfur dioxide, hydrogen sulfide, etc. (see US 4,847,059).

However, the catalyst itself introduces impurities into the product. These impurities are very detrimental to many applications of silicon tetrachloride in the semiconductor field and in optical fibers, for example, even trace amounts of boron in the ppm range are unacceptable.

(3) Preparation of silicon tetrachloride by using chlorosilane as a raw material

No. 3,754,077 discloses a process for reacting a mixture of chlorosilanes with carbon, alumina or silica to increase the content of silicon tetrachloride. JPH0699131, WO2015006173 and KR100134800 disclose a process for the preparation of silicon tetrachloride by reacting a mixture of HCl and a chlorosilane in the presence of a catalyst. Further, in the prior art, silicon tetrachloride as a by-product is also separated and recovered from a reaction product for preparing polycrystalline silicon or hydrosilane.

However, the above methods have problems such as low reaction yield and high impurity content, and it is impossible to obtain a large number of inexpensive four. Silicon chloride.

Therefore, there is a need to provide a method for industrially producing silicon tetrachloride on a large scale and at a low cost, and the method is simple in operation, and the obtained silicon tetrachloride impurity content is very small and the purity is high.

Summary of the invention

One embodiment of the invention relates to a method of producing silicon tetrachloride comprising the steps of:

The dried SiO ₂ powder, the carbonaceous material carbon powder and the chlorine gas are subjected to a chlorination reaction to obtain a silicon tetrachloride product.

The SiO ₂ product is obtained by using a dried SiO ₂ powder, a carbon elemental powder, and chlorine gas at a temperature of 800 to 1800 ° C to obtain a silicon tetrachloride product.

Drying the SiO ₂ powder and the carbon element powder;

The dried SiO ₂ powder and the carbon element powder are continuously fed to the reaction furnace with chlorine gas, and reacted at a temperature of 800 to 1800 ° C to obtain a silicon tetrachloride product.

According to one embodiment, the dried SiO ₂ powder and the carbon element powder are uniformly mixed before the reaction to obtain a mixture.

According to one embodiment, the present invention provides a method of industrially producing silicon tetrachloride, characterized by comprising the following successive steps:

a. separately grinding the SiO ₂ -containing substance and the carbon-containing elemental substance to obtain SiO ₂ powder and carbon powder;

b. drying the SiO ₂ powder and carbon powder;

c. uniformly mixing the dried SiO ₂ powder and the carbon powder to obtain a mixture;

d. The mixture and chlorine gas are continuously added to the reaction furnace, and reacted at a temperature of 800-1800 ° C to continuously produce a silicon tetrachloride product.

According to one embodiment, the SiO ₂ -containing material is 90%, preferably higher than 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% of the SiO ₂ content. Mineral raw materials.

According to an embodiment, the SiO ₂ -containing substance is selected from at least one of natural silica sand, silica, quartz sand, tridymite, and cristobalite.

According to an embodiment, the carbon-containing elemental substance is at least one of metallurgical coke, graphite powder, clean coal, or coke.

According to one embodiment, the SiO ₂ powder and the carbon powder have a particle size of 100-300 mesh, such as 100 mesh, 120 mesh, 150 mesh, 170 mesh, 200 mesh, 230 mesh, 250 mesh, 270 mesh or 300 mesh. .

According to one embodiment, the water content of the SiO ₂ powder and the carbon powder after drying is respectively less than 1% by weight, preferably less than 0.8% by weight, more preferably less than 0.5% by weight.

According to one embodiment, the dried SiO ₂ powder and the carbon powder are uniformly mixed in a molar ratio of SiO ₂ to carbon of from 1:2 to 1:4, preferably in a molar ratio of from 1:2 to 1:3, more preferably 1 : 2.5.

According to one embodiment, the reactor is an ebullated bed having a diameter greater than 1 m.

According to one embodiment, the mixture is heated with chlorine gas to 800-1800 ° C, preferably 1000-1500 ° C, such as 1050 ° C, 1100 ° C, 1150 ° C, 1200 ° C, 1250 ° C, 1300 ° C, 1350 ° C, 1400 ° C, 1450 ° C or 1500 ° C.

According to one embodiment, the chlorine gas is fed to the reaction furnace at an empty bed flow rate of from 0.005 to 0.05 m/s, preferably from 0.01 to 0.03 m/s.

According to one embodiment, the production process does not use a catalyst.

According to one embodiment, the resulting silicon tetrachloride product is free of hydrochlorosilane.

According to one embodiment, the resulting silicon tetrachloride product has a purity greater than 90%, preferably greater than 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99%.

The method for industrially producing silicon tetrachloride of the invention has moderate reaction conditions, simple process and low cost, and the obtained silicon tetrachloride product has high purity, and is a silicon-based industry, such as silicone, gas-phase white carbon black, and communication fiber. Rapid development provides raw material security. Since in the method of the present invention, the SiO ₂ powder and the carbon powder are dried before the reaction to remove moisture, the introduction of hydrogen in the reaction system is prevented, so that SiH ₂ Cl ₂ and SiHCl are not contained in the final product silicon tetrachloride. _3, etc. containing hydrochlorosilane. This increases the purity of the silicon tetrachloride and also reduces the difficulty and cost of subsequent silicon tetrachloride purification to some extent.

Detailed description of the invention

Source of raw materials

According to the invention, the SiO ₂ -containing material is any SiO ₂ content which can be purchased in large quantities above 90%, preferably above 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% mineral raw material. Although the raw material with less SiO ₂ content is easy to participate in the reaction, it will lead to the generation of too many bad by-products, reduce the purity of the product silicon tetrachloride, and increase the purification cost of the subsequent silicon tetrachloride, which is more difficult. The higher the SiO ₂ content, the more difficult it is to react with chlorine, and the higher the requirements for the reaction conditions. In the SiO ₂ -containing substance according to the present invention, the SiO ₂ content is most preferably higher than 90%, more preferably 95%, even more preferably higher than 97%.

The SiO ₂ -containing material according to the present invention is crystalline silica including, but not limited to, natural silica sand, silica, quartz sand, tridymite, cristobalite, and the like.

The carbonaceous material according to the present invention is a carbonaceous material which can be purchased in large quantities in the form of elemental carbon, including but not limited to: metallurgical coke, graphite powder, clean coal, activated carbon, charcoal, carbon black, smokeless carbon, coke, and the like.

The chlorine gas according to the present invention is commercially available, and the chlorine content is higher than 99.6%.

Dry, mixed

According to the present invention, the SiO ₂ powder and the carbon powder obtained after the grinding are required to be dried to remove moisture, and hydrogen is introduced into the reaction system to form hydrochlorosilane such as SiH ₂ Cl ₂ or SiHCl _{3 to} affect the quality of silicon tetrachloride. After drying, the water content of the SiO ₂ powder and the carbon powder are respectively less than 1% by weight, preferably less than 0.8% by weight, more preferably less than 0.5% by weight. Drying can be carried out using any drying equipment and techniques well known to those skilled in the art that meet the drying conditions of the materials to which the present invention relates.

Regularly check the content of hydrochlorosilane in the product silicon tetrachloride. If the content of the hydrochlorosilane is high, the drying is insufficient, and parameters such as drying temperature and time need to be adjusted to further reduce the moisture content in the raw material powder.

The dried SiO ₂ powder and the carbon powder are uniformly mixed in a molar ratio of SiO ₂ to carbon of from 1:2 to 1:4, preferably in a molar ratio of from 1:2 to 1:3, more preferably 1:2.5. The amount of toner can be slightly excessive to make the reaction more complete.

Reaction furnace

The reactor used in the silicon tetrachloride production method according to the present invention is preferably a bubbling bed. The use of the ebullating bed can increase the contact area between the chlorine gas and the mixture, increase the production strength, and the flowing powder can be easily added or taken out without affecting the progress of the reaction, thereby allowing the reaction to proceed continuously. In the present invention, mixed SiO ₂ powder and carbon powder are added to the reaction furnace, and then chlorine gas is introduced from the bottom of the reaction furnace to keep the powder in a boiling form at all times.

The temperature of the reaction furnace is controlled to be 800-1800 ° C, preferably 1000-1500 ° C, such as 1050 ° C, 1100 ° C, 1150 ° C, 1200 ° C, 1250 ° C, 1300 ° C, 1350 ° C, 1400 ° C, 1450 ° C or 1500 ° C. The empty bed flow rate for controlling the introduction of chlorine gas is from 0.005 to 0.05 m/s, preferably from 0.01 to 0.03 m/s. The flow rate is too low, the reaction efficiency is low, and it is not economical. The flow rate is too high, and the mixture is taken away, which affects the output.

In the present invention, the dried SiO ₂ powder and the carbon powder directly participate in the chlorination reaction in the reaction furnace without undergoing a granulation process, thereby avoiding the introduction of other impurities.

product

The silicon tetrachloride produced according to the method of the present invention has a large yield and a high purity. The resulting silicon tetrachloride product has a purity greater than 90%, preferably greater than 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99%. In particular, the silicon tetrachloride product produced according to the process of the invention does not contain hydrochlorosilanes such as SiH ₂ Cl ₂ , SiHCl ₃ and the like. Since in the method of the present invention, the SiO ₂ powder and the carbon powder are dried before mixing to remove moisture, thereby avoiding introduction of hydrogen into the reaction system, so that the final product silicon tetrachloride does not contain SiH ₂ Cl ₂ or SiHCl _{3 .} Hydrochlorosilane. This increases the purity of the silicon tetrachloride and also reduces the difficulty and cost of subsequent silicon tetrachloride purification to some extent.

Example

In order to further understand the present invention, a method for industrially producing silicon tetrachloride provided by the present invention will be described below with reference to the examples. The scope of protection of the present invention is not limited by the following examples.

Example 1

The commercially available silica sand (silica content greater than 95%) and coke are separately ground to a silica sand powder and carbon powder having a particle diameter of about 100 mesh, and the powder is dried to a water content of less than 1% by weight using a drying device, according to silica sand. : The mixture of carbon powder = 1:2.5 (molar ratio) was uniformly mixed to obtain a solid mixture. The mixture and chlorine were separately fed to the reactor in a continuous manner, wherein the amount of chlorine added was controlled at an empty bed flow rate of 0.03 m/s to maintain the mixture of the reactor in the form of a bubbling bed. The temperature of the reaction furnace was controlled at about 1450 ° C. The chlorine gas and the mixture were continuously produced in a gas-solid synthesis reaction in a reaction furnace at a high temperature to obtain silicon tetrachloride gas, and collected by a collection system to obtain a silicon tetrachloride condensate. The average purity of silicon tetrachloride was determined to be about 95%, the chlorine gas conversion rate was 93%, and hydrochlorosilanes such as SiH ₂ Cl ₂ and SiHCl _{3 were} not detected.

Example 2

The commercially available silica (silica content greater than 95%) and the clean coal are respectively ground into silica powder and carbon powder having a particle diameter of about 300 mesh, and the powder is dried to a water content of less than 1% by using a drying device. A ratio of silica sand:carbon powder = 1:3 (molar ratio) was uniformly mixed to obtain a solid mixture. The mixture and chlorine were separately fed to the reactor in a continuous manner, wherein chlorine gas was added at an empty bed flow rate of about 0.03 m/s to maintain the mixture of the reactor in an ebullated bed form. The temperature of the reaction furnace is controlled to about 1050 ° C. At a high temperature, the chlorine gas and the mixture are continuously produced by a gas-solid synthesis reaction in a reaction furnace to obtain silicon tetrachloride gas, and a silicon tetrachloride condensate is collected by a collecting system. It was determined that the average purity of silicon tetrachloride was about 90%, the conversion ratio of chlorine gas was 88%, and hydrochlorosilane such as SiH ₂ Cl ₂ or SiHCl _{3 was} not detected.

Example 3

The commercially available quartz sand (silica content greater than 97%) and metallurgical coke are respectively ground into quartz sand powder and carbon powder having a particle diameter of about 150 mesh, and the powder is dried to a water content of less than 1% by using a drying device. The mixture was uniformly mixed according to the ratio of quartz sand: carbon powder = 1:3 (molar ratio) to obtain a solid mixture. The mixture and chlorine were separately fed to the reactor in a continuous manner, wherein chlorine gas was added at an empty bed flow rate of about 0.03 m/s to maintain the mixture of the reactor in an ebullated bed form. The temperature of the reaction furnace is controlled at about 1150 ° C. At a high temperature, the chlorine gas and the mixture are continuously produced in a gas-solid synthesis reaction in a reaction furnace to obtain silicon tetrachloride gas, and the silicon tetrachloride condensate is collected by a collecting system. The average purity of silicon tetrachloride was determined to be about 95%, the chlorine gas conversion rate was 90%, and hydrochlorosilanes such as SiH ₂ Cl ₂ and SiHCl _{3 were} not detected.

Example 4

The commercially available cristobalite (silica content greater than 97%) and the graphite powder are separately ground to form a square quartz powder and carbon powder having a particle diameter of about 200 mesh, and the powder is dried to a water content of less than 0.8% by using a drying device. The mixture was uniformly mixed in a ratio of cristobalite:carbon powder = 1:2.5 (molar ratio) to obtain a solid mixture. The mixture and chlorine were separately fed to the reactor in a continuous manner, wherein chlorine gas was added at an empty bed flow rate of about 0.05 m/s to maintain the mixture of the reactor in an ebullated bed form. The temperature of the reaction furnace is controlled at about 1350 ° C. The chlorine gas and the mixture are continuously produced by a gas-solid synthesis reaction in a reaction furnace at a high temperature to obtain silicon tetrachloride gas, and a silicon tetrachloride condensate is collected by a collecting system. The average purity of silicon tetrachloride was determined to be about 95%, the chlorine gas conversion rate was 92%, and hydrochlorosilanes such as SiH ₂ Cl ₂ and SiHCl _{3 were} not detected.

Example 5

Commercially available scaly quartz (silica content greater than 96%) and charcoal were separately ground to form quartz silica powder and carbon powder having a particle size of about 170 mesh, and the powder was dried to a water content of less than 0.5% by weight using a drying apparatus. The mixture was uniformly mixed in a ratio of tridymite:carbon powder = 1:3 (molar ratio) to obtain a solid mixture. The mixture and chlorine gas were separately fed to the reactor in a continuous manner, wherein chlorine gas was added at an empty bed flow rate of about 0.04 m/s to maintain the mixture of the reactor in an ebullated bed form. The temperature of the reaction furnace was controlled at about 1200 ° C. The chlorine gas and the mixed material were continuously produced by a gas-solid synthesis reaction in a reaction furnace at a high temperature to obtain silicon tetrachloride gas, and a silicon tetrachloride condensate was collected by a collecting system. The average purity of silicon tetrachloride was determined to be about 96%, the conversion of chlorine gas was 90%, and hydrochlorosilane such as SiH ₂ Cl ₂ or SiHCl _{3 was} not detected.

Example 6

The commercially available silica (silica content greater than 98%) and activated carbon are separately ground to a silica powder having a particle size of about 230 mesh, carbon powder, and the powder is dried to a water content of less than 0.6% by weight using a drying apparatus, and silica is used. A ratio of carbon powder = 1:3 (molar ratio) was uniformly mixed to obtain a solid mixture. The mixture and chlorine were separately fed to the reactor in a continuous manner, wherein chlorine gas was added at an empty bed flow rate of about 0.02 m/s to maintain the mixture of the reactor in an ebullated bed form. The temperature of the reaction furnace is controlled at about 1350 ° C. The chlorine gas and the mixture are continuously produced by a gas-solid synthesis reaction in a reaction furnace at a high temperature to obtain silicon tetrachloride gas, and a silicon tetrachloride condensate is collected by a collecting system. The average purity of silicon tetrachloride was determined to be about 98%, the chlorine gas conversion rate was 92%, and hydrochlorosilanes such as SiH ₂ Cl ₂ and SiHCl _{3 were} not detected.

Comparative example 1

Commercially available silica sand (silica content greater than 95%) and coke were separately ground to a silica sand powder and carbon powder having a particle size of about 150 mesh, and uniformly mixed according to the ratio of silica sand: carbon powder = 1:2.5 (molar ratio). The solid mixture is not dried by the obtained silica sand powder and carbon powder. The mixture and chlorine were separately fed to the reactor in a continuous manner, wherein the amount of chlorine added was controlled at an empty bed flow rate of 0.03 m/s to maintain the mixture of the reactor in the form of a bubbling bed. The temperature of the reaction furnace is controlled at about 1350 ° C. The chlorine gas and the mixture are continuously produced by a gas-solid synthesis reaction in a reaction furnace at a high temperature to obtain silicon tetrachloride gas, and a silicon tetrachloride condensate is collected by a collecting system. The average purity of silicon tetrachloride was determined to be about 93%, the chlorine gas conversion rate was 94%, and about 0.7% of hydrochlorosilanes such as SiH ₂ Cl ₂ and SiHCl _{3 were} detected.

The above description is only for the preferred embodiment of the present application, and is not intended to limit the present application, and various changes and modifications may be made by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application are intended to be included within the scope of the present application.

Claims

A method of producing silicon tetrachloride, comprising the steps of:

The dried SiO 2 powder and the carbonaceous material carbon powder mixture are chlorinated with chlorine gas to obtain a silicon tetrachloride product.
A method of producing silicon tetrachloride, comprising the steps of:

Drying the SiO 2 powder and the carbonaceous carbon powder;

The dried SiO 2 powder and the carbonaceous material carbon powder and chlorine gas are continuously fed to a reaction furnace, and reacted at a temperature of 800 to 1800 ° C to obtain a silicon tetrachloride product.
A method of producing silicon tetrachloride, wherein the method comprises the following sequential steps:

a. separately grinding the substance containing SiO 2 and the carbonaceous substance to obtain SiO 2 powder and carbon powder;

b. drying the SiO 2 powder and carbon powder;

c. uniformly mixing the dried SiO 2 powder and the carbon powder to obtain a mixture;

d. The mixture and chlorine gas are added to the reaction furnace, and chlorination is carried out at a temperature of 800 to 1800 ° C to obtain a silicon tetrachloride product.
The method according to any one of claims 1 to 3, wherein the SiO 2 powder or the SiO 2 -containing material has a SiO 2 content of more than 90%, preferably more than 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% of mineral raw materials.
The method according to any one of claims 3 to 3, wherein the SiO 2 powder or the SiO 2 -containing substance is at least one selected from the group consisting of natural silica sand, silica, quartz sand, tridymite, and cristobalite.
The method according to any one of claims 1 to 3, wherein the carbonaceous material is at least one selected from the group consisting of metallurgical coke, graphite powder, clean coal, activated carbon, charcoal, carbon black, smokeless carbon, and coke. Kind.
The method according to any one of claims 1 to 3, wherein the SiO 2 powder and the carbon powder have a particle diameter of 100 to 300 mesh.
The method according to any one of claims 1 to 3, wherein the water content of the SiO 2 powder and the carbon powder after drying is less than 1% by weight, preferably less than 0.8% by weight, more preferably less than 0.5% by weight.
The method according to any one of claims 1 to 3, wherein the dried SiO 2 powder and the carbon powder are uniformly mixed in a molar ratio of SiO 2 to carbon of from 1:2 to 1:4 , preferably in a molar ratio of 1:2 to 1:3, more preferably 1:2.5.
The method according to any one of claims 1 to 3, wherein the reaction furnace is an ebullated bed having a diameter greater than 1 m.
The method according to any one of claims 1 to 3, wherein the chlorine gas is fed into the reaction furnace at an empty bed flow rate of 0.005 to 0.05 m/s, preferably 0.01 to 0.03 m/s.
The method according to any one of claims 1 to 3, characterized in that no catalyst is used during the reaction.
The method according to any one of claims 1 to 3, characterized in that the obtained silicon tetrachloride product does not contain hydrochlorosilane.
The method according to any one of claims 1 to 3, characterized in that the silicon tetrachloride product has a high purity At 90%, preferably greater than 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99%.